Lubricant for bearings operating in heated atmosphere



mica in between the wearin Patented 0a. 4, 1932' UNITED STATES. PATENT ol-"rlca JOHN 1'. BEHAVY, OI SAGINAW, IICHIGAN, ASSIGNOB TO BAKER PERKINS COMPANY,

INC 0! BAGINAW, IICHIGAN, A CORPORATION OF INIIHV YORK r-Unarcnzr ron rmmes ornnarme 1n HEATED ATMOSPHERE No Drawing.

This invention relates to a lubricant for bearing surfaces that operate in a heated atmosphere, for instance, the pintles of conveyor chains used in traveling bake ovens.

The object of my invention is to provide a liquid vehicle which is particularly effective for carrying finely divided graphite or surfaces and is possessed of a peculiar abllity to evaporate quickly and cleanly, leaving the graphiteor mica without leaving any other appreciable residue when the oven is "operated within its usual range of baking heats, namely from four hundred fifty degrees Fahren eit upwards.

After long experimentation- I have discovered a liquid vehicle that meets the above requirements and provides a wholly satisfactory means for lubricating the conve or chains of bake ovens and for other similar uses.

In practice its use over sufliciently' long periods of use has demonstrated that it completely solves the problem of producing an effective lubricant for bearings that have to work in a heated atmosphere, and that it willnot harden, gum or clog.-

Its use avoids the expense and labor heretofore entailed in periodically taking apart and cleaning by hand the se arate partsof bake oven conveyor chain arings to remove the hard resinous accretions that were formed by lubricants heretofore employed. The liquidvehicle which I have discovered is a light'refined petroleum oil havingthe following characteristics:.specific gravity 464 Baum, flash point 150 burn point 180, initial boiling point 370 1%., end boilingpoint 496 F.; at 440 F. 90 per cent of the oil will eva orate. i Y

I prepare this vehicle for use by stirring into it finely divided graphite in suitable proportions. Two -or three pounds of graphite to the gallon of oil gives good results, but the proportion of gra bite is not important as it may be adde up to the point where the mixture becomes too thick to penetrate between the surfaces to be lubriy, cated.

The above mentioned oil is suitable for Application ma Augult a, 1929. Serial no. 388,789.

the stated purpose primarily because of its boilin range. The initial boiling point, 370 ahrenheit, is high enough so it will not spatter or flash into vapor on striking the oven chains while they are at oven baking heat. It will wet the chain momentarily and run between. the bearing surfaces without :izlzling, carrying with it the graphite par 1c es. 1

Since the end boiling point, 496 Fahrenheit, of the oil is somewhat lower than the customary bread making temperature, the oil will evaporate virtually completely within a few minutes after its application, or if it has been applied to 'a cold chain it will evaporate while the oven is being heated up. Since none of the oil can remain long on the chain at baking temperatures, no harmful hard, resinous or carbon residue can be formed'by oxidation. At 450 Fahrenheit only a negligible amount of carbon will be formed since more than 90 per cent of the oil boils away at that temperature.

Heretofore, heavier oils used for oven chain. lubrication usually possessed a high per- 75 centage of high-boiling constituents which, w instead of evaporating, oxidized and built up hard carbon residue which wore the bearings and eventually caused the chain rollers to bind. So-called penetrating light oils were unsatisfactory for this kind of service, although they do not form carbon to the same extent as, the heavy oils above referred to, butthey do deposit an undesirable amount of reslnous or carbon cake. Furthermore, penetrating oils are relatively high priced, costing four to five times as much as the lubricant herein described.

Another advantage possessed by this hi hly refined oil is that it has a minimum of isagreeable odor.

Standard Oil Co.s No. 9 refined oil is a commercial product which possesses the characteristics required for the purpose of my invention. The lubricant made by mixing this oil with powdered or flake graphite may be applied to a newchain in a bake oven at least once a week, more often if necessary, until the working pf the chain become thoroughly coated 'w1th graphite. 9

a aeeopav Then the time between lubricatiqns may be extended, but'should always be systematic. When the chain is coated thoroughly, approximately one-half pint of lubricant at 5 each side of an ordinary oven conve er should be sufiicient, the amount de 11 ing upon the length ofthe chain. The lu ricantshould be applied while the oven is warm and empty'of bread. 4

1 I do not intend to limit myself to the use of an oil havin the precise specifications K given above, as t ose s cifications may vary somewhat and oils re ed by different producers may vary slightly without departing from my lnvention as claimed.

The essential qualification is that the oil shall have an end boiling point somewhat below the operating temperature of the parts to belubricated, in order that all of the oil 2Q shall evaporate from the lubricated surfaces quickl afiordin'g no time for formation of L solid e osits by oxidation. I find that most of the eposits on even chains are the result of oxidation of the. oil vehicle and gg-n'ot the-residue after 'eva ration.

Having thus describe my invention, what I claim and desire to secure by Letters Pat-' ent is: n

1. A lubricant for bake oven parts c'om-.

prising a mixture of finely divided graphite and petroleum oil having a-specific avi of approximately forty-six de ees aum an initial boiling point above t ree hundred twenty five de Fahrenheit and an end, as boiling point low five hundred degrees fFahrefiheit. p

i, '2. A lubricant for the heated mechanisms \of. bake ovens consisting ,of a mixture of.

comminuted dry lubricant and a light hydroso carbon oil initial boiling pomt of approximate] I hundred seventy de- (218% 811% an ialnd boilingi point o 'ap roxuna ve" undred v gl'e li 

